Mediastinal vacuum phenomenon: atypical pneumomediastinum caused by gas replacement of diminished fat

Abstract

We report a case involving an 83-year-old man with interstitial lung disease who developed atypical pneumomediastinum caused by gas replacement of diminished fat. The patient presented with a complaint of worsening symptoms of respiratory difficulty since a diagnosis of chronic eosinophilic pneumonia 5 months back. He had been under observation with no particular treatment for 5 months. Computed tomography performed on admission revealed pneumomediastinum. When the current scan was compared with that obtained 5 months ago, it was evident that the fat surrounding the mediastinum had been replaced by gas density. There was no mediastinal enlargement, pneumothorax, or pneumopericardium. Because the patient was elderly, home oxygen therapy was initiated for the interstitial pneumonia with no steroid therapy. Computed tomography performed 10 months after discharge showed the reappearance of mediastinal fat and no evidence of gas density. This case is unique because the pneumomediastinum was distinct from spontaneous pneumomediastinum caused by alveolar air leaks and resembled the vacuum phenomenon caused by intervertebral disc degeneration.

Negative Pressure Pneumomediastinum: A Novel Concept of Spontaneous Pneumomediastinum Without Mediastinal Widening Following Weight Loss

“…However, a case of a patient with ILD and PM without expansion of the mediastinal width has been reported previously. 4 In this case, the mediastinal fat decreased as a result of weight loss, and gas density appeared to replace the space. We presume that there is a decrease in the mediastinal pressure given that the space left following mediastinal fat loss is not substituted by lung expansion owing to low compliance of the lung in patients with ILD.…”

Negative pressure pneumomediastinum: a novel concept of spontaneous pneumomediastinum without mediastinal widening following weight loss

“…In some cases, upon the progression of respiratory failure, mediastinal enlargement results from air leaks owing to an increase in the intrapleural pressure, and is often associated with pneumothorax. However, a case of a patient with ILD and PM without expansion of the mediastinal width has been reported previously [3].…”